Butterfly

Tagged Questions

Refers to lenses in which focus is changed by moving internal lenses only. In contrast to "block focus" designs which focus by changing the distance of lens groups, or the entire lens, from the sensor.

The "IF" in Pentax DA★ 200mm f/2.8 ED (IF) SDM stands for "Internal Focus". I know what this means: the lens doesn't change in size as I focus. (And it's true; it doesn't.) What's the point of this, ...

The specification for the lens says that the Nikkor 18-105mm ED VR has the IF feature. However, the local market product label doesn't advertise this feature. How can I make sure that the IF feature ...